A known antiglare film such as disclosed in JP11-305010A includes a transparent base film, and an antiglare layer formed over the base film. The antiglare layer is formed of a material containing a transparent resin, and a diffusing material dispersed in the transparent resin and having a refractive index differing from that of the transparent resin by a value in the range of 0.01 to 0.5. The surface of the antiglare layer not facing the transparent base film has a haze value (external haze value) in the range of 7 to 30, and the antiglare layer has an internal haze value in the range of 1 to 15. This prior art antiglare film placed over the screen of an ordinary liquid crystal display substantially prevents scintillation (surface glaring), which causes the local glaring of images, and makes it possible to see excellent images having a high black density on a screen that does not become whitish.
The pixel density, i.e., the number of pixels in 25.4 sq. mm (1 sq. in.), of ordinary liquid crystal displays is in the range of about 100 to about 150 pixels/25.4 sq. mm. Therefore, the conventional antiglare film used in combination with such ordinary liquid crystal displays makes it possible to see images without any particular problems. However, it was found that problems arise when the conventional antiglare film is used in combination with liquid crystal displays having greater pixel densities.
For example, some high-definition liquid crystal displays have a pixel density in the range of about 200 to about 300 pixels/25.4 sq. mm, which is twice or greater than twice the pixel density of ordinary liquid crystal displays. One of the objects of increasing pixel density is to display images in a higher definition by a general purpose display, and another object is to provide a foldable display in the form of a flexible sheet and, more particularly, to provide a liquid crystal display sheet.
The liquid crystal display sheet can be used instead of a paper sheet carrying an image printed by a printer. When the liquid crystal display sheet is used for such a purpose, the image displayed by the liquid crystal display sheet is seen at close range and hence the image must be displayed in high definition. The image often includes many characters and lines. Since characters, differing from video pictures, are looked at deliberately, the characters become illegible if the characters have rugged outlines. Rugged lines also are illegible. Thus, the pixel density is increased to solve such problems.
When the conventional antiglare film is placed over the screen of a display having a pixel density twice that of the ordinary display, no particular problem arises in parts where openings in a black mask (or black matrix consisting of vertical and horizontal black lines) masking spaces between the pixels are coincident with protrusions of the antiglare film. However, it was found that parts where openings in the black mask are coincident with recesses of the antiglare film glare cause scintillation, seriously spoiling the visibility of characters, lines, pictures or photographs, particularly the visibility of characters and lines.
Glaring of parts where openings in the black mask are coincident with recesses of the antiglare film can be prevented when the diffuser content of the antiglare layer is increased by way of experiment, but the antiglare film tends to whiten, the transparency of the antiglare film decreases, and the transmission visibility and contrast of images are reduced. Thus, increase in the diffuser content of the antiglare layer is undesirable.